Improved spatial resolution in flat-panel imaging systems

John Yorkston, Larry E. Antonuk, Youcef El-Mohri, Kyung Wook Jee, Weidong Huang, Manat Maolinbay, Xiujiang Rong, Jeffrey H. Siewerdsen, David P. Trauernicht

Research output: Contribution to journalConference articlepeer-review

12 Scopus citations


Results of an investigation into the limiting spatial resolution of a flat-panel amorphous silicon (a-Si:H) X-ray imaging system are reported. The system was comprised of a 127 μm pixel pitch a-Si:H array used in conjunction with an overlying Gd2O2S:Tb (GOS) phosphor screen. The pre-sampled modulation transfer function (psMTF) of the system was measured at diagnostic X-ray energies and compared to the value predicted from a knowledge of the spatial resolution of the individual system components. A reproducible drop in the measured psMTF is seen at low spatial frequencies. Measurements of the magnitude of X-ray backscatter from the array substrate, along with the results of a theoretical model for K-fluorescence X-ray scatter, indicate that a significant fraction of this low-frequency drop is due to K-fluorescence from heavy elements in the glass substrate of the array. This K-fluorescence may be excited directly by primary X-rays that penetrate the overlying phosphor and interact in the glass, or by gadolinium K-fluorescence X-rays that escape from the phosphor into the glass. The measurements indicate that the spatial resolution of such an X-ray imaging system may be improved by the use of a substrate containing as low a concentration of heavy elements as possible.

Original languageEnglish (US)
Pages (from-to)556-563
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - Dec 1 1998
Externally publishedYes
EventMedical Imaging 1998: Physics of Medical Imaging - San Diego, CA, United States
Duration: Feb 22 1998Feb 24 1998


  • Amorphous silicon
  • Diagnostic imaging
  • Digital radiography
  • Flat-panel imager
  • K-fluorescence
  • Modulation transfer function (MTF)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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